Sand-bath



T. LIDBERG.

SAND BATH.

APPLICATION FILED APR. 19. 1920.

'1 78,474. Patented m 17,1921.

2 SHEETSSHEET I.

T. LIDBERG.

SAND BATH.

APPLICATION FILED APR. 19. 1920.

1 ,378,474:, Patented May 17, 1921.

2 SHEETS-SHEET 2- UNITED STATES PATENT OFFICE.

TIODOLF LIDIBERG, OF CHICAGO, ILLINOIS, ASSIGNOR TO CHICAGO SURGICAL AND ELECTRICAL COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SAN D-BATH.

Specification of Letters Patent.

Application filed April 19, 1920. Serial No. 374,794.

To all whom it may concern:

Be it known that I, TIODOLF LIDBEBG, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Sand-Baths, of which the following is a specification.

This invention relates to sand baths.

One of the objects of the invention 1s to provide an electrically heated sand bath of improved construction. I

nother object is to provide an eflicient structure adapted for use for many purposes, but especially adaptable for physicians, surgeons and chemists.

Another object is to providea new and improved means for heating the device, capable of regulation to produce a very 1ntelise, quickly acting temperature or a more moderate temperature, slow in action but more evenly distributed heat, and 1nterme diate temperature, the variations being obtainable by the simple act of rotating a snap switch element.

And still another object is to provide a bowl to contain the sand with the heating elements cemented to the convex side of the bowl to bring the heat as near to the sand to be heated as may practically be expedient.

Other, further and more specific objects of the invention will become readily apparent to persons skilled in the art from a consideration of the following description, when taken in conjunction with the draw ings, wherein Figure 1 is a perspective elevation of the device.

Fig. 2 is an enlarged inverted plan view of the removable heating element looking at it in the direction of the arrows on line 22 of Fig. 3.

Fig. 3 is a central section through the device.

' Figs. 4, 5, 6 and 7 show diagrams of circuits as they are controlled by the rotary snap switch.

In all of the views the same reference characters refer to similar parts.

The structure, as shown, consists of a box 10, mounted on four legs 11. It has four vertical side walls 12 and a removable top or cover 13. These parts and the bottom 14 are made preferably of vulca-beston or similar heat resisting material, The upright walls 12 may be oined at meeting ends by metal angle pieces 16 secured to the parts 12 by screws, or the like. Angle pieces 18 may be used to secure'the side walls to the bottom 14. A rotary snap switch 20 is secured to one of the side walls 12. The

- switch is provided with two spaced apart rotary blades 21 and 22, the former has three contact arms and the latter has two such arms. There are three stationary contacts associated with the blade element 21 and two with the blade element 22.

The cover 13 has a central opening to receive the bowl 23, which may be made of sheet metal with a flange 24, around its largest diameter, which rests upon the cover 13 and which is secured thereto by screws 25.

Over the convex surface of the bowl is applied a coating of insulating material 27, which is substantially unaffected by heat, then three groups of heating coils, groups A, B and C, then the coils are entirely submerged in the aforesaid insulating mastic after which a band 28 is secured to the cover 13, as at 29, to aid in holding the heating coils and the mastic in place on the underside of the bowl.

Now, referring to the diagram of circuits, the switch element 21 has blades 30-31 and 32 and stationary contacts 33, 34 and 35. The switch element 22 has two blades 36 and 37 and two stationary'coiiperating contacts 38 and 39.

The contacts and 29 are connected together by wire 40. Contact 38 is connected to group B of the heating coils by wire 41. Contact 33 is connected by wire 42 to the point 43, being thus connected to groups B and C of the coils. The wire 44 connects the point 43 to the group C. The contact 39 is connected to group A by wire 45 and groups A and C are connected together by the wire 46.

W hen the switch elements are in positions shown in Fig. 4, current will flow through groups A and C in series and throughv group B in parallel therewith, generating the highest temperature or most intense heat.

When the switch is rotated to occupy the positions shown in Fig. 5, then the current will pass through only group B and the heat will not be so great.

When the switch is again turned, the guts will occupy positions shown in Fig. 6.

0w the current passes through groups A,

Patented May 17, 1921. a

I before.

B and C in series and the current being thus reduced in value the heat will be less than When the switch is again turned until the parts are in positions shown in Fig. 7 the circuits through all of the groups of coils are all open.

In using the device sand is usually placed in the bowl and any object to be heated is placed in the sand. Thus test tubes, instruments and the like may be readily and uickly brought to the desired temperature.

1 course, the instrument is not limited in its use to the employment of sand as other substances may be substituted and liquid in some instances may be placed within the bowl.

While I have herein shown a single embodiment of my invention for the purpose of clear disclosure, it will be manifest that changes in the arrangement and configuration of the parts may be made within the sage of the appended claims.

aving described my invention what I claim as new and desire to secure by Letters Patent is 1. A heating device of the character described having a box; a bowl therein with its rim supported by the top of the box; a series of groups of heating coils attached to the convex surface of the bowl having their terminals within the box and a rotatable switch mounted on one side of the box arranged to connect the coils to vary their heat producing effect at different points in the rotation of the switch element.

2. A heating device of the character described having a rectangular box, the top of the box having an opening therein; a metal bowl within the opening having a rim secured to the margin of the opening; a series of heating coils secured by a substantially refractory adhesive to the convex surface of the bowl; a switch mounted on one of the side walls of the box operable to place the aforesaid coils in circuit in relation to vary their heat producing efi'ects, all live parts of the structure being inclosed within the box.

In testimony whereof I hereunto subscribe my name.

TIODOLF LIDBERG. 

